# NTSB CEN10CA434: Air Tractor 502B, N4203B, Whittemore, IA, July 23, 2010

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Data collection · Final report
- Date: July 23, 2010, 14:00 local (19:00 UTC)
- Place: Whittemore, IA
- Coordinates: 43.063056, -94.422775 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=43.0631&lon=-94.4228&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Defining event: [Takeoff: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report December 20, 2010
- Report: Approved by Office Director
- NTSB office: Central Region
- Parties: FAA Des Moines FSDO
- NTSB case key (mKey): 76747
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN10CA434
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76747/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76747
- Page: https://openairdocs.org/ntsb/CEN10CA434

## Probable cause

The pilot's failure to abort the takeoff, which resulted in an aerodynamic stall.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md)
- [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md)
- [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Takeoff: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) (defining event); cases with it: [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md)
- [Takeoff: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)

## Analysis

The pilot reported that he had made four previous agricultural aerial application runs prior to the accident flight, one of which had the same load as the accident flight. He departed to the north since the windsock was indicating a slight northeast wind. The grass airstrip was about 2,640 feet long and was soft due to recent rains. The weather was about 90 degrees Fahrenheit with high humidity. He reported that he put in 10 degrees of flaps, held the brakes, and ran the engine up to 1,700 lbs of torque. After he released the brakes and started the takeoff roll, the airplane encountered a soft spot in the runway, which reduced his ground speed. Halfway down the runway the tail had still not come up, so the pilot “forced the tail up using the trim tab” and by pushing the stick full forward. The pilot eased the forward stick pressure and the tail went back to the ground. He immediately began to dump the load and he put in full flaps. About 100 yards before the end of the runway, the pilot “pulled the stick all the way back and became airborne, but stalled [the] airplane.” The left wing stalled and impacted the ground. The airplane came to rest in a corn field on the edge of the grass airstrip. The pilot reported that he “should have stopped the ground roll when I encountered the wet spot in the strip.” The airplane sustained substantial damage to the left wing, right wing, and empennage.

## Factual narrative

The pilot reported that he had made four previous agricultural aerial application runs prior to the accident flight, one of which had the same load as the accident flight. The grass airstrip was about 2,640 feet long and was soft due to recent rains. The weather was about 90 degrees F with high humidity. He put in 10 degrees of flaps, held the brakes, and ran the engine up to 1,700 lbs of torque. He departed to the north since the windsock was indicating a slight northeast wind. After he released the brakes and started the takeoff roll, the airplane encountered a soft spot in the runway which reduced his ground speed. Halfway down the runway the tail had still not come up, so the pilot “forced the tail up using the trim tab” and by pushing the stick full forward. The pilot eased the forward stick pressure and the tail went back to the ground. He immediately began to dump the load and he put in full flaps. About 100 yards before the end of the runway, the pilot “pulled the stick all the way back and became airborne, but stalled [the] airplane.” The left wing stalled and impacted the ground. The airplane came to rest in a corn field on the edge of the grass airstrip. The pilot reported that he “should have stopped the ground roll when I encountered the wet spot in the strip.” The airplane sustained substantial damage to the left wing, right wing, and empennage.

## Aircraft

- Registration: N4203B (not matched to a registry record)
- Reported make and model: AIR TRACTOR 502B
- Category: Airplane
- Serial number: 502B-2636
- Engines: Pratt & Whitney PT6A-34AG turbo prop
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Josh Aukes
- Registered owner: A&M Flying Service
- Airworthiness certificate: Special, Restricted (Special)
- Departed: Whittemore, IA
- Destination: Whittemore, IA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 29; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2; flight hours: 3,468 total, 1,598 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Lowest ceiling: none

## Docket (1 files)

The files NTSB released with the investigation on September 8, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76747. 889 KB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 889 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40335371&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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